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White Gold
Pure gold is slightly reddish yellow in color, but colored gold in various other colors can be produced by alloying gold with other elements. Colored golds can be classified in three groups: * Alloys with silver and copper in various proportions, producing white, yellow, green and red golds. These are typically malleable alloys. * Intermetallic compounds, producing blue and purple golds, as well as other colors. These are typically brittle, but can be used as gems and inlays. * Surface treatments, such as oxide layers. Pure 100% (in practice, 99.9% or better) gold is 24 karat by definition, so all colored golds are less pure than this, commonly 18K (75%), 14K (58.5%), 10K (41.6%), or 9K (37.5%). Alloys White gold White gold is an alloy of gold and at least one white metal (usually nickel, silver, or palladium). Like yellow gold, the purity of white gold is given in karats. White gold's properties vary depending on the metals used and their proportions. As a result, white gol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wristwatch
A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached by a watch strap or other type of bracelet, including metal bands, leather straps or any other kind of bracelet. A pocket watch is designed for a person to carry in a pocket, often attached to a chain. Watches were developed in the 17th century from spring-powered clocks, which appeared as early as the 14th century. During most of its history the watch was a mechanical device, driven by clockwork, powered by winding a mainspring, and keeping time with an oscillating balance wheel. These are called '' mechanical watches''. In the 1960s the electronic ''quartz watch'' was invented, which was powered by a battery and kept time with a vibrating quartz crystal. By the 1980s the quartz watch had taken over most of the market from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrum
Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. Its color ranges from pale to bright yellow, depending on the proportions of gold and silver. It has been produced artificially, and is also known as " green gold".Emsley, John (2003Nature's building blocks: an A–Z guide to the elements Oxford University Press. . p. 168 Electrum was used as early as the third millennium BC in Old Kingdom of Egypt, sometimes as an exterior coating to the pyramidions atop ancient Egyptian pyramids and obelisks. It was also used in the making of ancient drinking vessels. The first known metal coins made were of electrum, dating back to the end of the 7th century or the beginning of the 6th century BC. For several decades, the medals awarded with the Nobel Prize have been made of gold-plated green gold. Etymology The name "electrum" is the Latinized form of the Greek word ἤλεκτρον (''ḗlektron''), mentioned in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Persian
Ancient history is a time period from the beginning of writing and recorded human history to as far as late antiquity. The span of recorded history is roughly 5,000 years, beginning with the Sumerian cuneiform script. Ancient history covers all continents inhabited by humans in the period 3000 BCAD 500. The three-age system periodizes ancient history into the Stone Age, the Bronze Age, and the Iron Age, with recorded history generally considered to begin with the Bronze Age. The start and end of the three ages varies between world regions. In many regions the Bronze Age is generally considered to begin a few centuries prior to 3000 BC, while the end of the Iron Age varies from the early first millennium BC in some regions to the late first millennium AD in others. During the time period of ancient history, the world population was already exponentially increasing due to the Neolithic Revolution, which was in full progress. While in 10,000 BC, the world population stood ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffusionless Transformations
A diffusionless transformation is a phase change that occurs without the long-range diffusion of atoms but rather by some form of cooperative, homogenous movement of many atoms that results in a change in the crystal structure. These movements are small, usually less than the interatomic distances, and the neighbors of an atom remain close. The systematic movement of large numbers of atoms led to some to refer to these as ''military'' transformations in contrast to ''civilian'' diffusion-based phase changes, initially by Frederick Charles Frank and John Wyrill Christian. The most commonly encountered transformation of this type is the martensitic transformation which, while probably the most studied, is only one subset of non-diffusional transformations. The martensitic transformation in steel represents the most economically significant example of this category of phase transformations, but an increasing number of alternatives, such as shape memory alloys, are becoming more im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium
Aluminium (aluminum in AmE, American and CanE, Canadian English) is a chemical element with the Symbol (chemistry), symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and Passivation (chemistry), forms a protective layer of Aluminium oxide, oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, Magnetism, non-magnetic and ductility, ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of Aluminum-26, 26Al is used in Radiometric dating, radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Gold
Crown gold is a 22 karat (kt) gold alloy used in the crown coin introduced in England in 1526 (by Henry VIII). In this alloy, the proportion of gold is 22 parts out of 24 (91.667% gold)—and is appreciably less prone to wear than the softer 23 kt gold of earlier gold sovereigns—an important point for coins intended for everyday use in circulation. Alloying metal The alloying metal in England was, and is, traditionally restricted to copper. This is still used for the current British gold sovereign. An exception was for the gold sovereigns of 1887, when 1.25% silver, replacing the same weight of copper, was used to gain a better reproduction image of Queen Victoria for the Golden Jubilee of her reign. Elsewhere, both copper and silver have been used in varying proportions. Circulating coins In the United States until 1834, gold circulating coins were minted in 22 kt. crown gold—although using about 6% silver as well as copper. From 1834, the fineness of U.S. coin gold was d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle East
The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabia (including the Arabian Peninsula and Bahrain), Asia Minor (Asian part of Turkey except Hatay Province), East Thrace (European part of Turkey), Egypt, Iran, the Levant (including Ash-Shām and Cyprus), Mesopotamia (modern-day Iraq), and the Socotra Archipelago (a part of Yemen). The term came into widespread usage as a replacement of the term Near East (as opposed to the Far East) beginning in the early 20th century. The term "Middle East" has led to some confusion over its changing definitions, and has been viewed by some to be discriminatory or too Eurocentric. The region includes the vast majority of the territories included in the closely associated definition of Western Asia (including Iran), but without the South Caucasus, and additionally includes all of Egypt (not just the Sinai Region) and all of Turkey (not just the part barring East Thrace). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic table. In some respects, zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size.The elements are from different metal groups. See periodic table. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States. Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity ( electrowinning). Zinc is an essential trace element for humans, animals, plants and for microorganisms and is necessary for prenatal and postnatal development. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jewelry
Jewellery (British English, UK) or jewelry (American English, U.S.) consists of decorative items worn for personal adornment, such as brooches, ring (jewellery), rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a western perspective, the term is restricted to durable Ornament (art), ornaments, excluding flowers for example. For many centuries metal such as gold often combined with gemstones, has been the normal material for jewellery, but other materials such as glass, shells and other plant materials may be used. Jewellery is one of the oldest types of archaeological artefact – with 100,000-year-old beads made from ''Nassarius'' shells thought to be the oldest known jewellery.Study reveals 'oldest jewellery' , ''BBC News'', June ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rose Gold Diamond Engagement Ring
A rose is either a woody perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be erect shrubs, climbing, or trailing, with stems that are often armed with sharp prickles. Their flowers vary in size and shape and are usually large and showy, in colours ranging from white through yellows and reds. Most species are native to Asia, with smaller numbers native to Europe, North America, and northwestern Africa. Species, cultivars and hybrids are all widely grown for their beauty and often are fragrant. Roses have acquired cultural significance in many societies. Rose plants range in size from compact, miniature roses, to climbers that can reach seven meters in height. Different species hybridize easily, and this has been used in the development of the wide range of garden roses. Etymology The name ''rose'' comes from La ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( ) from the Greek words, ''hydor'' (water) and ''argyros'' (silver). A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature. Mercury occurs in deposits throughout the world mostly as cinnabar ( mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide. Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, mercury relays, fluorescent lamps and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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